1. Field of the Invention
This invention relates to improvements in a side door hinge mechanism in a motor vehicle through the utilization of a quadric rotary link mechanism.
2. Description of the Related Art
In most cases, the side door in a motor vehicle, e.g. passenger can has heretofore been installed in a manner to be rotatable about a hinge affixed to a vehicle body for opening or closing. In order to allow an occupant of the motor vehicle to open or close the side door for getting in and out of the motor vehicle, a door opening angle commensurate to the total length of the side door is required. At this time, when a space outwardly of the motor vehicle is small, there are many cases where it is difficult for the occupant to get in and out of the vehicle because the side door cannot be opened sufficiently.
In contrast thereto, as disclosed in Japanese Utility Model Laid-Open (Kokai) No. 46014/1982 or 101263/1980 for example, there has been proposed a side door hinge mechanism through the utilization of a quadric rotary link mechanism, wherein the quadric rotary link mechanism comprises: a rotary link interconnecting a point on a body of vehicle and another point on a side door as rotary centers out of two points spaced apart from each other on the body and two points spaced apart from each other on the side door; another rotary link interconnecting the other point on the body and the other point on the side door as being centers; a portion between the two rotary centers on the body; and another portion between the two rotary centers on the side door.
The side door hinge mechanism utilizing the above-described quadric rotary link mechanism makes it possible for the occupant to reduce the necessary space outwardly of the motor vehicle while securing a space at his feet. In consequence, even when the space outwardly of the motor vehicle is small, the occupant can get in and out of the motor vehicle by opening or closing the side door.
In the side door hinge mechanism utilizing the above-described quadric rotary link mechanism, the rotary center shaft of the side door is spaced apart a rotary link's length from the rotary center shaft of the body, whereby a moment acting on the side door hinge due to a load of the side door becomes high and also a high load due to this moment is applied to a portion for mounting the rotary center shaft of the side door.
In consequence, in order to increase the rigidity for supporting the side door, it is necessary to mount a plurality of door hinges arranged in the vertical direction.
However, when the plurality of side door hinges are mounted in the vertical direction as described above, such disadvantages are presented that these rotary center shafts should be aligned with each in the vertical direction and the works of mounting and adjusting are troublesome.
Further, the rigidity of the surfaces of the body and the side door, to which the above-described rotary center shafts, particularly, the rigidity of the surface of the side door should be made considerably high. To satisfy this requirement, such a disadvantage is presented that the weights of the side door and of the door hinge should be increased.
More specifically, if the rigidity of the side door is low, then, in conjunction with the long length of the door hinge, i.e. the rotary link, for example the rigidity in the vertical direction, torsional rigidity and rigidity for bearing an excessive opening of the side door when the side door is opened become low, such disadvantages are presented that the side door is displaced downwardly, distorted or deformed when fully opened.
Further, if the rigidity is low when the door is closed, such a disadvantage is presented that ill-fitting to the body occurs.
In particular, since only one second rotary link is provided downwardly in the side door hinge described in the above-described Japanese Utility Model Laid-Open (Kokai) No. 127314/1979, the load of the side door in the vertical direction and the opening-closing direction is borne only by the torsional rigidity of the first rotary link and the resultant force of the side door, thus presenting the disadvantage of that the rigidity as a whole is low.